The Endophthalmitis Vitrectomy Study (EVS) is a prospective, randomized, multicenter clinical trial designed to determine the role of pars plana vitrectomy in the initial management of patients with bacterial endophthalmitis. This is an application to serve as Coordinating Center for this study, with primary responsibility for study organization, data management and statistical analysis. The accompanying Study chair application presents the study protocol and includes as appendices the manual operation and data collection forms. Investigators from the Epidemiology Data Center at the University of Pittsburgh propose to continue to work with the Study Chair and other clinical investigators to make final revisions to study protocol, manual of operations and data collection forms. The Coordinating Center will be responsible for preparing the randomized scheme, interim monitoring and reporting to the Safety and Data Monitoring Committee. Data will be received, processed and managed on the Data Center system of IBM microcomputers and mainframe VAX. The trial will compare treatment strategies for endophthalmitis and as such "intention to treat" will be primary method of analysis. Analysis methods will be developed and tested during data acquisition phases and final analysis and reports will be generated during the last phase.